Restoring mailboxes from backup duplicates messages in POP clients

[Luis F. V. Gomes]

Hello
>
> I had a disk problem and had to reformat it. All mailboxes were backed 
> up using rsync.
> After I restored the mailboxes, the POP clients (Thunderbird) that 
> were configured to leave the messages on the mailserver for, let's 
> say, 30 days, didn't understand that some messages were already 
> transfered and the users got duplicated messages in their Inbox.
> How can we avoid this?
>

-- 
Thanks
Luís Fernando V. Gomes
IT Manager
(55)(21) 3527-1220
Departamento de Engenharia Elétrica
PUC-Rio
R. Marques de S. Vicente 225/401L
22451-900 - Rio de Janeiro/RJ - BR